1. Field of the Invention
The invention relates to an image color adjusting technique.
2. Description of the Related Art
When images are taken using image-generating devices such as digital still cameras and video cameras, the entire image is processed by what is referred to as color balancing. The color balancing technique is disclosed, for example, in JP3469305B, JP11-205806A, JP10-210494A, and JP2-128591A.
Color balancing is done to reduce colorcast in images in order to allow the photographed subject to be accurately reproduced in the original white color. Such color balancing is often done using white areas which are nearly achromatic, and is thus also referred to as white balancing.
However, the colors in the image can turn into various colors according to the colors of the photographed subject, and can also turn into various other colors (color cast) depending on the color of the light source. Thus, in color balancing, color deviation is evaluated using various colored components which are nearly achromatic in order to reduce various types of colorcast. However, conventional color balancing has not taken into consideration the distribution of colors which are nearly achromatic in the processed image.
This problem is not limited to color balancing processes, but also pertains to processes for adjusting image colors.
Another problem concerning color balancing is that it is sometimes not possible to accurately reproduce the original colors no matter how much RGB color components is adjusted in order to compensate for light source differences.